I 'm planning to use 3D-printed parts in my hobby project. I uploaded a test model to Shapeways and received it printed. I'm very happy with the material and finish but have a question about shrinkage.

Shapeways model checker showed the dimensions as cm: 4.36 w x 6.46 d x 5.22 h which is correct. When I measured the printed piece it was 4.29 W x 6.25 d x 5.06 h so the shrinkage varied from 1.6% to 3.3% in different directions.

Is this what I should expect? Or was I unlucky? I glanced the forums and found conflicting answers to this. One of the tutorials appears to say that shrinkage is taken care of and should not be a problem, of course to a certain accuracy.

I think I can work around that amount of shrinkage but should I be prepared for even more? Or even expansion?

This amount of shrinkage is not acceptable and I would contact customer services for a re-print.
I have had only 1 experience of this amount of model under-sizing and it was quickly replaced FOC.
I add 2% to my patterns as they are used as masters for metal castings.